linux-kernel - [PATCH for 4.9 41/59] USB: serial: mos7720: fix control-message error handling

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Message-ID: <20170914155051.8289-41-alexander.levin@verizon.com>
Date:   Thu, 14 Sep 2017 15:51:16 +0000
From:   "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Johan Hovold <johan@...nel.org>,
        "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
Subject: [PATCH for 4.9 41/59] USB: serial: mos7720: fix control-message error
 handling

From: Johan Hovold <johan@...nel.org>

[ Upstream commit 0d130367abf582e7cbf60075c2a7ab53817b1d14 ]

Make sure to log an error on short transfers when reading a device
register.

Also clear the provided buffer (which if often an uninitialised
automatic variable) on errors as the driver currently does not bother to
check for errors.

Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Johan Hovold <johan@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 drivers/usb/serial/mos7720.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index 136ff5e1b7c1..135eb04368f9 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -234,11 +234,16 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
 
 	status = usb_control_msg(usbdev, pipe, request, requesttype, value,
 				     index, buf, 1, MOS_WDR_TIMEOUT);
-	if (status == 1)
+	if (status == 1) {
 		*data = *buf;
-	else if (status < 0)
+	} else {
 		dev_err(&usbdev->dev,
 			"mos7720: usb_control_msg() failed: %d\n", status);
+		if (status >= 0)
+			status = -EIO;
+		*data = 0;
+	}
+
 	kfree(buf);
 
 	return status;
-- 
2.11.0